Cat urine on unprimed color-field painting

Steven Prins <sprins1102<-a t->aol< . >com> writes

>I have received in my studio for treatment a color-field painting on
>unprimed canvas that has been marked with urine by a male cat.  I am
>wondering if anyone on the list has recent references regarding
>feline urine composition and chemistry, as well as
>conservation-appropriate procedures and formulae for its removal
>from unprimed canvas? Thanks in advance for any references and/or
>suggestions.

The three main compositions of feline urine are urea, urochrome, and
uric acid.

Urea is the sticky component of the urine--visible when drying out.

Urochrome is the yellowish pigment of the urine--fluorescent under
UV light.

Uric acid is composed of non-soluble salt crystals that are
reactivated with moisture--even moisture in the air--giving off the
distinctive smell. The chemical composition of cat urine varies
depending on the age, health condition and diet of the cat (type of
food, access to food -i.e periodic or continuous etc.). Generally,
other than urea, uric acid and urochrome, you may expect phosphates,
sulphates, chloride, nitrogen, creatinine, creatine, protein,
ammonia, calcium, magnesium etc and various levels of pH.

You may find more information at

    Alastair N. Worden, C.E. Waterhouse, E.H.B. Sellwood (1960)
    "Studies on the Composition of Normal Cat Urine", in Journal of
    Small Animal Practice, Volume 1, Issue 1-4, pages 11-23,
    February 1960
    <URL:http://onlinelibrary.wiley.com/doi/10.1111/j.1748-5827-1960.tb06044.x/abstract>

    Y.H. Cottam, P. Caley, S. Wamberg, and W.H. Hendriks (2002)
    "Feline Reference Values for Urine Composition", in Waltham
    International Symposium: Pet Nutrition Coming of Age, The
    Journal of Nutrition, June 1, 2002 vol. 132 no. 6
    1754S-1756S
    <URL:http://jn.nutrition.org/content/132-6-1754S.full.pdf+html>

    Finco D.R., Adams D.D., Crowell W.A., Stattelman A.J., Brown
    S.A., Barsanti J.A. (1986)
    "Food and water intake and urine composition in cats: influence
    of continuous versus periodic feeding", in American Journal of
    Veterinary Research 1986 July, 47(7):1638-42.
    <URL:http://www.ncbi.nlm.nih.gov/pubmed/3740638>

To successfully remove feline urine crystals -which are tougher than
dirt and grease, and therefore traditional cleaning methods won't
work on them- you should chemically break down the uric acid.
Enzymatic cleaners are quite successful in breaking down the stain
and smell. Some home remedies include Hydrogen Peroxide 3%, vinegar,
liquid detergents and baking soda. Avoid steam cleaning, as this may
cause the smell and stain to set more into the fibers. Do not use
brown vinegar-use only white vinegar. Do not mix hydrogen peroxide
with vinegar as this will create peracetic (aka peroxyacetic) acid,
an oxidising acid, which at high concentrations can be corrosive and
cause irritations.

Here is a "traditional" home remedy for old and dried cat urine
stains on fabric:  First thoroughly wet the area with a solution of
50% white vinegar and 50% deionised water. Do not use brown vinegar,
as this may cause staining. Dry out by blotting with blotting paper
and paper towels and use a wet/dry vacuum extractor to remove excess
moisture. Then apply a handful of baking soda over the affected
area. Mix a quarter of a cup of 3% hydrogen peroxide with a teaspoon
of liquid non caustic detergent and drizzle it over the baking soda.
Work it well into the fibres with a soft brush. Allow to dry
completely and then vacuum up the dried baking soda or use a brush
to remove it. Remember not to mix vinegar and hydrogen peroxide as
this will cause toxic vapours.

Evangelia Kyriazi, MSc
Conservator of Antiquities and Works of Art
Adjunct conservation lecturer of the Technological Educational
    Institute of the Ionian Islands
Department of Protection and Conservation of Cultural Heritage


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                  Conservation DistList Instance 27:16
                  Distributed: Sunday, October 6, 2013
                       Message Id: cdl-27-16-006
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